EP2915651A1 - Method for the production of blow moulded plastic hollow bodies and multiple extrusion head for carrying out the method - Google Patents

Abstract

The invention relates to a method for producing blow-molded hollow plastic body, in which tubular preforms (10) of at least two juxtaposed extrusion tools (2) of a Mehrfachextrusionskopfes (1) extruded simultaneously and blow mold cavities (4) of a closing unit (3) are supplied, in which the preforms (10) are expanded by blowing air to plastic hollow bodies (13) after closing the Blasformkavitäten (4). The preforms (10) emerge from a nozzle gap (s) of the extrusion dies (2) delimited by a mandrel (6) and a nozzle body (3). The die gap width (s) of the extrusion dies (2) is changed during extrusion by adjusting movements of the mandrels (6) and / or by an adjusting movement of the nozzle bodies (7). The melt distribution of the preforms (10) emerging from the extrusion dies (2) is changed in the circumferential direction in each case by deformation and / or displacement of an elastic sleeve (17) delimiting the die gap (s) during the extrusion. Each extrusion tool (2) is assigned at least one program-controlled individual drive (18), which acts by means of a transmission element (19) only on the elastically deformable sleeve (17) of the associated extrusion tool (2). The transmission elements (19) engage in the area between adjacent extrusion tools (2) and are effective there on a peripheral portion of the elastically deformable sleeve (17) associated with the individual drive (18).

Description

The invention relates to a method for producing blow-molded hollow plastic body, are extruded at the same time tubular extrusions from at least two juxtaposed extrusion dies of a Mehrfachextrusionskopfes and blow mold cavities of a closing unit, in which the preforms are expanded after closing the Blasformkavitäten by blowing air to hollow plastic bodies, and a Mehrfachextrusionskopf to carry out the process. A multiple extrusion head for carrying out such a process is for example out EP 0 575 039 A1 known.

In the extrusion of the preforms an equal tube run of the preforms is sought. Furthermore, the preforms should have the same length and an equal melt distribution at the time of closing the blow mold cavities. The extrusion tools may have separate housings or be arranged together in a housing. Likewise, it is within the meaning of the invention that the multiple extrusion head consists of one unit or is formed of a plurality of juxtaposed individual extrusion heads. It is possible that each extrusion die is fed by a plasticizing unit. Alternatively, the extrusion dies can also be connected to a central extruder via a melt distribution arrangement. The wall of the tubular preforms emerging from the extrusion dies can be single-layered or have a coextruded multilayer structure.

Out DE 10 2007 030 677 B4 For example, a multiple extrusion head for a blow molding machine is known which has a plurality of juxtaposed ones in a row Includes extrusion tools. The extrusion dies extend parallel to a mold parting plane of the blow mold cavities and each have a mandrel and a nozzle body surrounding the mandrel. The mandrel and the nozzle body form an annular nozzle gap whose gap width is variable by an axial adjustment of the mandrel or the nozzle body.

During extrusion, the nozzle gap width of all extrusion tools is changed by synchronous positioning movements of the mandrels and / or by synchronous adjusting movements of the nozzle body. This gives the preforms in the axial direction a changing wall thickness profile, which is adapted to the subsequent blow molding process so that the blow-molded plastic hollow body over its entire length have a predetermined wall thickness.

In the manufacture of large volume blow molded containers, e.g. As plastic fuel tanks, it is common in practice, not only to influence the wall thickness distribution of the exiting the extrusion die preform in the discharge but also in the circumferential direction during the extrusion dynamic. To change the melt distribution in the circumferential direction elastically deformable sleeves have proven to form a wall portion of the nozzle gap and are elastically deformed during extrusion by a program-controlled power drive. The method and suitable devices are made DE 28 23 999 C2 and US 6,284,169 B1 known.

Multiple extrusion heads, which have a plurality of juxtaposed in a row tools are used in blow molding equipment to produce inexpensive plastic hollow body, the example-wise for liquid personal care products, cleaning agents, motor oils and the like are used and usually have a filling volume between 200 ml and 2.5 l. These intended as packaging for consumer products plastic hollow body often differ from a cylindrical shape or a canister shape and have for example the shape of an oval bottle, often in conjunction with a handle recess or a molded handle. In order to be able to produce complex container shapes with a defined uniform wall thickness, it is necessary to change the die gap geometry during the extrusion of the preforms as a function of the extrusion length between a circular ring shape and a geometry deviating from the circular ring shape.

In the publication " Kunststoffe ", issue 12/2010, pages 124 to 127 An extrusion tool is described which allows a melt distribution of a preform in the circumferential direction. The designed as a retrofit kit has a nozzle body with two flanged electric actuators and an elastically deformable sleeve. In order to adjust the nozzle gap optimally, it is necessary that the actuators act in the mold parting plane of Blasformkavitäten on the sleeve. In cramped installation conditions arise mounting problems. If the blow molding plant has a plurality of extrusion dies which are arranged next to one another in a row, the stitch spacing between the extrusion dies determines the available installation space. If the stitch spacing is small, the use of the tool is not possible.

Against this background, the invention has for its object to provide a method for producing blow-molded plastic hollow body, which is suitable for cramped installation conditions for the operation of a Mehrfachextrusionskopfes and on the extrusion dies of Multiple extrusion head allows dynamic profiling of the nozzle gap in the circumferential direction. The technical implementation of the process should be simple and inexpensive and thus allow a quick return on investment with full production security.

The object of the invention and solution of this problem is a method according to claim 1.

The invention requires a method for producing blow-molded hollow plastic body, in which tubular preforms of at least two juxtaposed Extrusionswerk witnesses a Mehrfachextrusionskopfes simultaneously extruded and blow mold cavities are fed to a closing unit in which the preforms are expanded after closing the Blasformkavitäten by blowing air to hollow plastic bodies. The preforms emerge from a nozzle gap of the extrusion dies delimited by a mandrel and a nozzle body, the die gap width of the extrusion tools being changed during extrusion by adjusting movements of the mandrels and / or an adjusting movement of the die bodies. According to the invention, the melt distribution of the preforms emerging from the extrusion dies is changed in the circumferential direction in each case by deformation and / or displacement of an elastic sleeve delimiting the die gap during the extrusion. For this purpose, a program-controlled single drive is assigned to each extrusion tool, which acts by means of a transmission element only on the elastically deformable sleeve of the associated extrusion die. The transmission elements in each case engage in a region between two adjacent extrusion tools and are effective there on the circumference of the elastically deformable sleeves. By means of the program-controlled individual drives and their associated transmission elements, the melt distribution of the preforms in the circumferential direction of the preforms are dynamically controlled during the extrusion of the preforms. In this case, the position and orientation of the individual drives can be determined independently of the position of the force application point between the transmission element and sleeve. The method according to the invention can therefore be used without restrictions even if the extrusion tools are arranged with a small stitch spacing in a row next to each other. The method according to the invention always makes it possible to optimally define the force-acting direction of the transmission elements acting on the circumference of the sleeves, independently of the position of the individual drives.

The force is transmitted locally from the transmission element to the sleeve in at least one force application point. The transmission elements in each case act on at least one force application point on the circumference of the sleeves. The force application point can be set in a peripheral portion of the sleeve, which is oriented up to ± 45 ° obliquely to the mold parting plane of Blasformkavitäten. By determining the point of force application, an optimization is possible without thereby the position of the extrusion tool associated with the individual drive would have to be changed. Usually, the force application point between the sleeve and the transmission element is in a peripheral portion of the sleeve, which extends over an angle of a maximum of ± 22.5 ° with respect to the mold parting plane of the blow mold cavities.

Preferably, the transmission element acts on at least one force application point on the circumference of the sleeve, which lies in the mold parting plane of the Blasformkavitäten, wherein the force acting direction of the transmission element is aligned in the force application point radially to the central axis of the sleeve. In this arrangement, the transfer element acts in the main deformation axis, which lies in the mold parting plane, on the elastically deformable sleeve.

In most cases, the blow mold cavities are positioned below the extrusion dies for receiving the preforms. Alternatively, the preforms extruded from the extrusion dies can be gripped by means of a gripper and then fed to the blow mold cavities so that the mold parting plane and the orientation of the extrusion dies can be offset. In this case, the feature that the point of application of force between the transfer element and the sleeve lies in the mold parting plane of the blow mold cavities is realized when the portion of the tubular preform adjacent to the point of force application lies in the mold parting plane when the blow mold cavity closes.

The inventive method is particularly suitable for the production of hollow plastic containers, which are used for packaging of liquid products and have the shape of a bottle with molded handle or handle recess. The containers mentioned are characterized, inter alia, by the fact that they are mirror-symmetrical to the mold parting plane, while they have an asymmetrical shape transversely to the mold parting plane. The containers formed from the blow mold cavities have at their upper and lower ends a squeeze seam or a waste slug which extends over portions of the container.

To carry out the method according to the invention, elastically deformable sleeves are preferably used which have a defined over the entire circumference continuous deformation behavior at a point-like initiation of acting on the circumference radial force. By actuating the individual drives, the forces for deformation of the sleeves locally applied to the sleeve at the periphery of the sleeves, which deforms continuously under the action of these forces in the circumferential direction. In this case, due to the interaction between the locally introduced forces and the internal forces and moments generated thereby over the entire circumference of the sleeve forms a defined profile. A cylindrical sleeve can be obtained by introducing local forces, for example, an oval shape. Preferably elastically deformable sleeves are used, which are made of one piece single-walled.

To increase the positioning accuracy, it is advantageous to set the adjusting movement of the individual drives so that a large displacement on the drive side has a small deformation movement of the sleeve result. By the corresponding increase in the restoring forces in the deformation movement can then be used comparatively small and therefore cost-effective drives. A reduction can for example be realized by a mechanical transmission, in particular a toggle lever arrangement.

The extrusion dies are arranged side by side in a row or rows. The deformation of all in a row juxtaposed sleeves is preferably carried out in the same deformation axis, wherein the deformation axis coincides with an axis of the juxtaposed extrusion dies and extends in the mold parting plane or parallel to the mold parting plane.

A first, particularly simple embodiment of the method according to the invention provides that the transmission elements act in an adjusting movement of their associated drive on an outer circumferential surface of the sleeves and that the sleeves arranged on at least one circumference Supported abutment and / or tethered. The anvil is expediently arranged offset by 180 ° to the force application point of the transmission element. The sleeves can also be supported on a plurality of abutments arranged on its circumference. Due to the number and position of the abutment, the deformation geometry can be influenced. Are counter-bearing and / or transmission elements at least indirectly connected to the sleeve, the deformation of the sleeve can be done both by pressure and by tensile forces.

The transmission element may have a hinge arrangement which acts on the sleeve.

It is also within the scope of the invention to use sleeves which have a defined ovality in the relaxed state. The sleeves are conveniently installed so that the major axis of the sleeves lies in the axis of deformation. The Überragungselemente lie against the sleeve, but without having to be firmly connected to this. The use of pre-ovalized sleeves is particularly suitable for adjusting elements, which are preferably not firmly connected to the sleeve.

The transmission element associated with a single drive can have kinematically coupled elements which act in pairs on the sleeve and exert radial pressure forces or tensile forces on the associated sleeve on both sides during an adjusting movement of the individual drive. If only compressive forces act on the sleeves, both single-walled and multi-layered sleeves (flex rings) can be used. If the sleeves are also deformed by tensile forces, no multi-layer flex rings can be used; instead, single-walled sleeves are preferably used. Are the transmission elements positively connected or hingedly connected to the sleeves, pulling forces can be transmitted in the described embodiment.

If equally large tensile or compressive forces are applied to the sleeves on the shell side, then the sleeves - especially if single-walled sleeves are used - symmetrically deformed. The cross section of the sleeve takes on at least in the plane in which the radial tensile and / or compressive forces are applied to an oval cross-section or at least one approximated to an ellipse basic shape. Depending on the bearing of the sleeve and / or the position of the force application point in the extrusion direction, the deformation of the sleeve by the force in the longitudinal direction is constant or reaches a maximum value from a minimum value at the sleeve inlet to the nozzle outlet.

The method according to the invention is not limited to the fact that the sleeves are only elastically deformed by pressure or tensile forces acting radially on the lateral surface of the sleeves. In the context of the invention, it is also possible that the sleeves are pivoted or radially displaced by acting in the radial direction compressive or tensile forces. Sliding, swiveling and deformation movements can be combined with one another in order to greatly change the geometry of the nozzle gap during the extrusion of the preforms. By the combination of radially acting tensile and compressive forces which offset by 180 ° to each other attack on the circumference of the sleeve, the sleeves can be moved sideways and depending on the storage of the sleeves either pivoted or moved radially. If radial adjusting movements are carried out with different travel, the sleeves can both be elastically deformed and at the same time be moved sideways in the radial direction. In all these cases, a very strong profiling of the die gap geometry is possible. The elastically deformable sleeves can be supported on a horizontal surface of a carrier. Alternatively, the sleeves can be performed vertically movable or tiltably mounted at its upper end in the extrusion tool. By means of transmission elements, which act on the nozzle outlet end of the sleeves and are pivotally connected to the sleeves, the sleeves can be pivoted.

The force application points of the transmission elements are expediently determined in all previously described embodiments of the method according to the invention to the sleeves so that their direction of force is aligned with the mold parting plane of Blasformkavitäten.

According to a preferred embodiment of the method according to the invention, two program-controlled individual drives are associated with each extrusion tool of the multiple extrusion head, which act by means of associated transmission elements only on the elastically deformable sleeve of the associated extrusion head and exert tensile forces or compressive forces on a lateral surface of the sleeve. By program-controlled adjusting movement of the two individual drives, the sleeve is deformed, pivoted or moved radially. The sleeves can be deformed in each case by opposing, in the amount equal adjustment paths of the transmission elements acting on them. The sleeves can be further deformed by the amount different adjustment paths and pivoted in the direction of the axis of deformation or moved radially. Finally, the sleeves can be pivoted or displaced radially by rectified, equal adjustment movements of the transmission elements without deformation.

In the extrusion tools independent basic settings can be made, in the course of these settings, the sleeves are pre-formed and / or the position of the sleeves is corrected and / or the nozzle body and the mandrel are adjusted relative to each other. The possibility of being able to make independent basic settings on the extrusion dies is advantageous, since in the production of small blow-molded hollow bodies, even small differences in the die gap from one extrusion die to the other extrusion die result in significant wall thickness differences of the blow-molded hollow bodies. It should also be considered that the extrusion dies can be supplied with plastic melt by a plasticizing unit or also by a plurality of plasticizing units. Both variants can lead to rheological differences between the individual preforms for various reasons. The rheological behavior of the plastic melt, manufacturing tolerances in the flow channels of the extrusion dies and a temperature influence can lead to the tube run of the preforms issuing in parallel from the extrusion dies and the radial wall thickness distribution of the individual preforms differing from one another. For the purpose of correction, the extrusion tools therefore preferably have individually assigned actuating elements which can be actuated independently of each other for changing a basic setting of the nozzle gap geometry.

The invention also provides a multi-extrusion head suitable for carrying out the described method according to claim 10.

The basic structure of the multiple extrusion head includes at least two juxtaposed extrusion tools, each having a mandrel and a nozzle body delimiting nozzle gap. Several extrusion tools can be arranged side by side. The extrusion tools can be individually attached to the Multiple extrusion head may be mounted or arranged to realize a rapid assembly process on a common carrier, which is connected to the multiple extrusion head. The extrusion tools are each equipped with at least one elastically deformable sleeve, which forms a wall portion of the nozzle gap and is arranged in the nozzle body of the extrusion die. Each extrusion tool is associated with at least one program-controlled single drive, which acts by means of a transmission element only on the elastically deformable sleeve of the associated extrusion die. The transmission elements each engage in the area between adjacent extrusion tools and are effective there on a peripheral portion of the elastically deformable sleeve associated with the individual drive. As means of transmission, any means can be used which act on an outer circumferential surface of the sleeves and transmit pressing or pulling movements on the sleeves.

Preferably, the transmission elements have a linkage which underpins a control stroke of the individual drive connected to the linkage into a smaller travel which is effective on the elastically deformable sleeve.

Fig. 1A

eine mit einem Mehrfachextrusionskopf ausgestattete Blasformanlage zur Herstellung blasgeformter Kunststoffhohlkörper in einer Seitenansicht,

Fig. 1B

eine stark vereinfachte Draufsicht auf die Extrusionswerkzeuge des in Fig. 1A dargestellten Mehrfachextrusionskopfes,

Fig. 2

einen Längsschnitt durch ein Extrusionswerkzeug aus der Blickrichtung A in Fig. 1B,

Fig.3

einen Schnitt durch den in Fig. 2 dargestellten Mehrfachextrusionskopf in der Schnittebene II-II der Fig. 2,

Fig. 3 bis 11

Schnittdarstellungen von Ausgestaltungen des Mehrfachextrusionskopfes, wobei Fig. 5 den in Fig. 2 dargestellten Mehrfachextrusionskopf in der Schnittebene II - II der Fig. 2 zeigt,

Fig. 12A, 12B

eine Exzenteranordnung zur Verstellung und/oder Deformation einer elastischen Hülse eines Extrusionswerkzeuges,

Fig. 13

eine weitere Ausgestaltung der in Fig. 12A/12B dargestellten Exzenteranordnung,

Fig. 14

eine Schieberanordnung zur Verstellung und/oder Deformation einer elastischen Hülse eines Extrusionswerkzeuges,

Fig. 15

eine vorteilhafte Ausgestaltung des Mehrfachextrusionskopfes in einer Schnittdarstellung.

Advantageous embodiments of the multiple extrusion head according to the invention are described in the patent claims and explained below with reference to exemplary embodiments. They show schematically:

Fig. 1A

a blow molding machine equipped with a multiple extrusion head for producing blow-molded hollow plastic bodies in a side view,

Fig. 1B

a simplistic plan view of the extrusion tools of the Fig. 1A shown multiple extrusion head,

Fig. 2

a longitudinal section through an extrusion tool from the viewing direction A in Fig. 1B .

Figure 3

a section through the in Fig. 2 shown multiple extrusion head in the sectional plane II-II of Fig. 2 .

Fig. 3 to 11

Sectional views of embodiments of the multi-extrusion head, wherein Fig. 5 the in Fig. 2 shown multiple extrusion head in the sectional plane II - II of Fig. 2 shows,

Figs. 12A, 12B

an eccentric arrangement for adjusting and / or deformation of an elastic sleeve of an extrusion tool,

Fig. 13

another embodiment of in Fig. 12A / 12B shown eccentric arrangement,

Fig. 14

a slider arrangement for adjusting and / or deformation of an elastic sleeve of an extrusion tool,

Fig. 15

an advantageous embodiment of the Mehrfachextrusionskopfes in a sectional view.

In the Fig. 1A schematically shown blow molding plant comprises a Mehrfachextrusionskopf 1 with a plurality of juxtaposed extrusion dies 2, a closing unit 3, which has a number of extrusion dies corresponding number of Blasformkavitäten 4, and an actuator 5 for the simultaneous adjustment of a nozzle gap in the extrusion dies 2. Die Extrusionswerkzeuge 2 sind in a row next to each other and extend parallel to a mold parting plane x, z of Blasformkavitäten 4. The extrusion dies 2 each have a mandrel 6 and a nozzle body 7 surrounding the mandrel 6 with a nozzle gap s. The extrusion tools 2 may have independent housing or be integrated in a housing. The extrusion dies 2 are connected via a melt distributor 8 with a plasticizing unit 9, z. B. an extruder connected. The plastic melt exits in the form of tubular preforms 10 from the juxtaposed extrusion tools 2. In this case, the nozzle gap width s of the extrusion dies 2 is changed during the extrusion of the preforms 10 by adjusting movements of the mandrels 6 and / or by an adjusting movement of the nozzle body 7. The control of this movement, for example, by means of an actuator 5, which is connected via a crossbar 11 with the individual extrusion tools 2 and performs programmable positioning movements 3 according to specification of a profile curve 12 shown schematically. Instead of an actuator 5, which is connected via a crossmember 11 with the individual extrusion dies 2, the extrusion dies 2 can also be associated with individual actuators which execute program-controlled setting movements.

The preforms 10 are supplied to the blow mold cavities 4 of the closing unit 3 and expanded there after the closing of the blow mold cavities 4 by blowing air to hollow plastic bodies 13. In the embodiment will be Plastic bottles formed in the mold parting plane x, z of Blasformkavitäten 4 have an asymmetric design and have a substantially symmetrical profile in a vertical sectional plane y, z.

The blow mold halves 14, 14 'which are separated along the mold parting plane x, z are generally mounted on tool clamping plates of a closing unit 3. The closing unit 3 takes over the closing of the two blow mold halves 14 14 'against the preforms during extrusion blow molding. During this mold closing movement, the preforms 10 are closed by squeezing protruding preform material. Weld seams 15, which are referred to as squeeze seams, are produced in the squeezing zones as a result of the welding of the plastic tube. The squeezed plastic residues are referred to as slugs 16 and removed as waste pieces of the plastic hollow body 13. During or after closing the Blasformkavitäten the preforms 10 are inflated with compressed air and pressed against the cooled Wandungskavität. Depending on the extrusion and blowing process, the closing unit 3 remains under the multiple extrusion head 1 or is moved from the extrusion region of the preforms 10 in a so-called blowing position. It also corresponds to the prior art that multiple locking units 3 are assigned to the multiple extrusion head 1.

The extrusion tools 2 are each equipped with at least one elastically deformable sleeve 17 which forms a wall section of the nozzle gap s and is arranged in the nozzle body 7 ( Fig. 2 ). The sleeve 17 is radially movably supported on a horizontal surface 21 of a carrier 22 and guided vertically movable at its upper end in the extrusion die 2. Alternatively, the sleeve 17 at its upper end also be stored tiltable in the extrusion tool 2. The sleeves 17 are usually made of metal and are thin-walled. Other sleeve materials, eg. As temperature-resistant plastics and composite materials can also be used. Preference is given to sleeves 17 which can be deformed both by radial compressive forces and by radial tensile forces. During the extrusion of the preforms 10, the cross-sectional geometry of the sleeves 17 is changed in order to influence the profile of the nozzle gap s. For the purpose of radial elastic deformation of the sleeves 17, each extrusion tool 2 of the multiple extrusion head 1 is assigned at least one program-controlled individual drive 18, which acts by means of a transmission element 19 only on the elastically deformable sleeve 17 of the associated extrusion tool 2.

The transmission elements 19 act on a peripheral portion of the elastically deformable sleeves 17, which extends over an angle of a maximum of ± 45 ° relative to the x-axis of the mold parting plane. The force is transmitted locally in the force application point 20 on the sleeve 17 and is aligned in the force application point 20 radially to the central axis of the sleeve 17. Typically, the force application point 20 is located between the sleeve 17 and the transmission element 19 in a peripheral portion of the sleeve 17, which extends over an angle of ± 22.5 ° with respect to the x-axis of the mold parting plane.

Preferably, the transmission element 19 acts on at least one in the mold parting plane x, z force application point 20 on the circumference of the sleeve 17. In this arrangement, the transmission element 19 in the main deformation axis, which is in the mold parting plane x, z acts on the elastically deformable sleeve 17th The individual drives 18 assigned to the transmission elements 19 are offset laterally relative to the x-axis of the mold parting plane arranged. The position and orientation of the individual drives 18 can be independent of the in Fig. 2 shown force application point 20 (between the transmission element 19 and the sleeve 17) are set.

In the embodiment of Fig. 3 press the transmission elements 19 in an adjusting movement in each case on one side to an outer circumferential surface of the sleeves 17, which are supported on a plurality of arranged on its circumference abutments 23. The number and position of the abutment 23 influences the cross-section of the sleeves 17, which is adjusted by the elastic deformation during the actuation of the unidirectional transmission elements 19. In the exemplary embodiment, three abutment 23 are provided, which are arranged at equidistant intervals on the circumference of the sleeves 17, wherein one of the abutment is positioned offset by 180 ° to the point of force application of the transmission element 19 and defines the deformation axis together with the force application point 20. In this case, the sleeve 17 can be connected to the counter bearing. In the exemplary embodiment, the deformation axis extends parallel to the mold parting plane x, z of the blow mold cavities 4. If the transfer element 19 is connected to the flexible sleeve 17, pulling deformations can also be carried out. The individual drives 18 for adjusting the transmission elements 19 may have a pneumatic, hydraulic or electromechanical drive head.

In the embodiment of Fig. 4 has the transmission 18 associated with a single transmission element 19 kinematically coupled elements 24, 24 ', which act in pairs on the sleeve 17 and exert on both sides compressive or tensile forces on the associated sleeve 17 at an actuating movement of a only schematically indicated by a pinion single drive 18.

In the embodiment of Fig. 5 The individual drives 18 each have an electromechanical drive head 25 for generating a linear movement of an element 24, which cooperates with a linearly movable actuating element 24 '. The drive head comprises a geared motor with two output shafts driven in opposite directions. The elements 24, 24 'perform kinematically coupled counter-rotating movements. In addition, the sleeves 17 may be supported on counter bearings 23. Preferably, four abutment 23 are provided, which are aligned at an angle α of ± 45 ° to the deformation axis. The deformation axis is defined by the force application points 20 of the kinematically coupled elements 24 and extends parallel to the mold parting plane x, z of the Blasformkavitäten 4. The elements 24, 24 'of the transmission element 19 are connected by a hinge with the sleeve 17 so that compressive forces and tensile forces can be transferred to the sleeve.

In the extrusion tools 2 independent basic settings can be made, in the course of these settings, the sleeves 17 of the extrusion dies 2 are pre-formed and / or the position of the sleeves 17 is corrected and / or the nozzle body 7 and the mandrel 6 of the extrusion dies 2 are adjusted relative to each other , To change the basic setting of the extrusion tools 2 associated and independently operable actuating elements are provided.

In the embodiment of Fig. 4 are the kinematically coupled elements 24, 24 'adjusting elements 26, 26' are arranged, which act radially on the wall surface of the associated sleeve 17. By actuating these adjusting elements 26, 26 ', in each case the sleeve 17 assigned to the adjusting element can be deformed or corrected with respect to its position. Furthermore, adjusting elements 27, 27 'are provided which act on the nozzle body 7 of the extrusion dies 2 and allow a position correction of the nozzle body 7 relative to the mandrel 6 of the extrusion die. The change of a basic setting on the extrusion dies 2 is advantageous, since in the production of small blow-molded hollow bodies, even a small difference in the radial die gap profile from one extrusion die to the other extrusion die results in large wall thickness differences of the preforms 10. It is therefore advantageous that, to compensate for manufacturing tolerances, each transmission element 19 acting on the sleeve 17 has compensation elements. Furthermore, the rheological behavior of the plastic melt and manufacturing tolerances in the flow channels of the extrusion dies 2 and temperature differences can cause the tube run of the preforms 10 emerging from the extrusion dies 2 and the radial wall thickness distribution of the preforms 10 emerging from different extrusion dies 2 to diverge. To correct these effects, it may be expedient if the basic shape of the sleeves and their position can be corrected on each sleeve 17 by the described adjusting elements 26, 26 '. The same applies to a correction of the position between the nozzle body 7 and mandrel 6 using the adjusting elements 27, 27 '.

In the embodiment of Fig. 5 has the transmission 18 associated with a single transmission element 19 kinematically coupled elements 24, 24 ', which act in pairs on the sleeve 17 and 18 execute an opposite movement of the pliers during an adjusting movement of the individual drive. As shown in Fig. 5 the drive 18 is designed as a spindle drive and has a motor with a reduction gear and counter-rotating threaded spindles. The kinematically coupled elements 24, 24 'of the transmission elements are connected by spindle nuts to the threaded spindles. Each extrusion tool is a program-controlled one Assigned individual drive 18, which acts by means of kinematically coupled elements 24, 24 'of a transmission element 19 only on the elastically deformable sleeve 17 of the associated extrusion die 2.

The transmission elements 19 can also be designed as a slide 28, wherein the slide 28 each have a control surface which cooperates with a counter surface on the associated sleeve 17. Such a constructive solution is in Fig. 6 shown. The control surfaces consist of a chamfered end of the slide 28. The slide 28 exert pressure in an adjusting movement on both sides of the associated sleeve 17 and deform this elliptical. The slides 28 are guided between pressure plates 30 whose position can be adjusted by adjusting means 29. By adjusting the pressure plates 30, individual basic settings can be made on the extrusion tools 2. As part of this basic setting, the position of the sleeves 17 can be corrected individually. Furthermore, an individual pre-deformation of the sleeves 17 is possible.

The connection region between the transmission element 19 embodied as a slide 28 and a sleeve 17 can be designed such that tensile forces are transmitted to the lateral surface of the sleeves 17 during an actuating movement of the transmission elements 19 and the sleeves 17 are deformed elliptically by tensile forces acting on both sides. In this case, the sliders 28 act on control surfaces which are connected to the sleeves 17. The connection region between the transmission elements 17 and the sleeves 17 can also be designed such that a traction or a compressive force is transmitted to the sleeves 17 in an adjusting movement of the transmission elements 19 as a function of the travel. A corresponding connection element 31 is in Fig. 7 shown. The transmission element 19 engages in the connection element 31, which with the Shell of the sleeve 17 is connected and control surfaces 32 for transmitting radial compressive forces and control surfaces 32 'for transmitting radial tensile forces.

In the in Fig. 6 and 7 illustrated embodiments, the slider 28 are aligned horizontally. It is understood that vertically oriented slides can be used which act by vertical positioning movements on control surfaces on the circumference of the sleeve, wherein pressure forces and / or tensile forces can be transmitted in the manner described. An arrangement with two vertically aligned slides 28 is shown in FIG Fig. 14 shown. By coordinated movements of the two slides 28, the sleeve 17 can be pivoted in the direction of the deformation axis x or moved radially, wherein the in Fig. 14 set nozzle geometry shown between the mandrel 6 and nozzle body 7 can be set. Trained as a slide 28 transmission elements engage in connection elements 31, which are connected by positive locking elements 43 releasably connected to the sleeve 17. The elastically deformable sleeve 17 is exchangeable, without the connection elements 31 and the associated transmission elements must be removed.

The Fig. 8 shows a transmission element 19, which is designed as a rotary ring 34. The rotary ring has at a circumferential surface adjacent to the sleeve 17 at least one control surface 33 which cooperates with a counter-surface 35 on the sleeve 17 during a rotational movement of the rotary ring 34 and exerts pressure on the associated sleeve 17. Each of the parallel-connected extrusion tools 2 can be equipped with a rotary ring 34, wherein each rotary ring 34 is associated with a program-controlled single drive 18. In addition, abutment 23 may be provided for supporting the sleeve 17.

In the embodiment of Fig. 9 have the transmission elements 19 kinematically coupled elements 24, 24 ', which act in pairs on the transmission element 19 associated sleeve 17 and exert on both sides of pressure or tensile forces on the sleeve 17 upon actuation of the extrusion tool associated with individual drive 18. The elements 24, 24 'are hinged to the sleeve 17 and connected via a toggle lever assembly 36 to the single drive 18. In the case of the toggle lever arrangement 36 illustrated in the exemplary embodiment, a two-fold reduction with respect to the travel results from the fact that the levers of the toggle lever arrangement 36 are supported on stationary pivot points 37. At the same time, there is an increase in the actuating force corresponding directly to the transmission elements 19.

In the embodiments of the Fig. 10 . 11 . 12 and 15 Each programmable individual drives 18, 18 'are associated with each extrusion tool 2 of the multiple extrusion head 1, each acting by means of a transmission element 19, 19' only on the elastically deformable sleeve 17 of the associated extrusion head and exert tensile forces or compressive forces on a lateral surface of the sleeve 17. By program-controlled adjusting movements of the two individual drives 18, 18 ', the sleeve 17 can be deformed, pivoted or radially displaced. The transmission element 18, 18 ', for example, as a toggle lever assembly as shown in FIG Fig. 10 or as a slider accordingly Fig. 11 or as an eccentric arrangement with a rotatably mounted eccentric shaft 38 (FIG. Figs. 12A, 12B be formed, wherein the eccentric shaft 38 and the slider 28 has a control surface which cooperates at the force application point 20 with a counter surface on the circumference of the sleeve 17.

The eccentric arrangement is in Fig. 12A excerpts in a side view and in Fig. 12B shown in a plan view. The eccentric arrangement comprises an eccentric shaft 38 that can be driven in rotation by a single drive and that has an eccentric element 39 arranged thereon. The eccentric element 39 has a control surface which is effective on the circumference of the sleeve 17. By a rotational adjustment of the eccentric shaft 38, a pressure force for deformation and / or adjustment of the sleeve can be exerted on the sleeve 17.

According to a in Fig. 13 illustrated embodiments of the eccentric engages the formed in the form of an eccentric shaft transmission element 19 in a connection element 31, which is connected to the sleeve 17. The connection element and the eccentric element 39 have control surfaces 32, 32 'for transmitting radial pressure or tensile forces. The connection element can - as in Fig. 13 represented - be designed as an eye.

In the embodiments of the Fig. 10 to 13 the transmission elements are aligned horizontally. Instead, a vertical orientation of the transmission elements is possible.

According to a in Fig. 15 illustrated advantageous embodiment of the device according to the invention, the transmission elements 19 each have a linkage 44, which sets a setting stroke h ₁ of the linkage 44 connected to the individual drive 18 in an effective on the elastically deformable sleeve 17 smaller travel h ₂ . The linkage 44 allows the simultaneously effective power transmission that lower-power and cost-effective actuators can be used as individual drives 18. Suitable actuators are, for example, simple standard stepper motors with spindle drive. The linkage 44 has in the embodiment of Fig. 15 a lever 45 which at one end in a bearing 50 pivotally is mounted and is pivotally connected at its other end to an actuator 46 of the single drive 18. Between the lever 45 and the elastically deformable sleeve 17, a transmission element 47 is provided for transmitting movement, which is connected to a coupling point 48 between the force application point 49 of acting on the lever 45 single drive 18 and the end bearing 50 to the lever 45. The connection to the coupling point 48 can be done for example by means of a ball joint. By the aspect ratio l ₁ / l of the lever portion l ₁ between the bearing 50 and the coupling point 48 on the one hand and the total length l of the lever 45 between the bearing 50 and the force application point 49 of acting on the lever 45 single drive 18 on the other hand, the reduction ratio can be varied. Preferably, the distance between the coupling point 48 and the bearing 50 is as small as possible and the distance between the coupling point 48 and the force application point 49, at which the individual drive 18 acts on the lever 45, as large as possible. In the exemplary embodiment, the bearing 50 for the pivotable mounting of the lever 45 is arranged on a carrier 51, which is connected to the extrusion die 2. Other constructions should not be excluded. An advantage of in Fig. 15 illustrated embodiment of the invention is the compact design. In cramped installation conditions, a large reduction ratio between the control stroke h _{1 of} the individual drive 19 and acting on the deformable sleeve 17 stroke h ₂ can be realized, which may be for example 10: 1 to 100: 1. It is also within the scope of the invention for the desired reduction ratio to be realized by means of a two-stage or multi-stage reduction.

The device according to the invention enables a dynamic influencing of the radial nozzle gap profile in parallel juxtaposed

Extrusion tools 2 a multiple extrusion head 1, which can be arranged with a small distance from each other. The device according to the invention and the claimed method can also be realized in confined spaces of a multiple extrusion head 1 and are suitable for small nozzle diameters, in particular for diameters of significantly less than 60 mm. The described methods and devices can be combined in any way. By means of a wall thickness control, the sleeves 17 of the extrusion dies 2 are deformed simultaneously, wherein a radial displacement or a radial pivoting of the sleeves is possible. The extrusion tools 2 may have separate nozzle bodies 7, or else form a nozzle body assembly which is horizontally adjustable or tiltable as a unit. Preferably, the nozzle body 7 are arranged horizontally adjustable or tiltable. At least one drive is provided in order to adjust the nozzle body 7 relative to the spikes 6 of the extrusion tools 2. The direction of action of the drive acting on at least one nozzle body 7 can be aligned with the deformation axis predetermined by the force application points 20 of the transmission elements 19 or extend parallel to a deformation-neutral axis of the sleeves 17. It is also expedient if the extrusion tools individually assigned and independently operable adjusting elements for changing a basic setting of the nozzle gap geometry are assigned. Appropriately, therefore, adjusting elements are arranged on the transmission elements, wherein the basic setting of the extrusion tool can be changed by a pre-deformation and / or a position correction of the sleeve by actuation of these adjusting elements.

Claims (29)

Method for producing blow-molded hollow plastic bodies, in which tubular preforms (10) are extruded from at least two juxtaposed extrusion tools (2) of a multiple extrusion head (1) and blow mold cavities (4) are fed to a closing unit (3) in which the preforms (10) move the closing of the blow mold cavities (4) by means of blown air to plastic hollow bodies (13) are widened,
wherein the preforms (10) emerge from a nozzle gap (s) of the extrusion dies (2) delimited by a mandrel (6) and a nozzle body (3) and the die gap width (s) of the extrusion dies (2) during extrusion by actuating movements of the mandrels ( 6) and / or the nozzle body (7) is changed,
wherein the melt distribution of the preforms (10) emerging from the extrusion dies (2) is changed in the circumferential direction in each case by deformation and / or displacement of an elastic sleeve (17) delimiting the die gap (s) during the extrusion,
wherein each extrusion tool (2) is assigned at least one program-controlled individual drive (18) which acts by means of a transmission element (19) only on the elastically deformable sleeve (17) of the associated extrusion tool (2), and
wherein the transmission elements (19) in each case engage in a region between two adjacent extrusion dies (2) and are effective there on the circumference of the elastically deformable sleeves (17). A method according to claim 1, characterized in that the transmission elements (19) each act on at least one force application point (20) on the circumference of the sleeves (17), wherein the force application point (20) is located in a peripheral portion of the sleeve (17) referring to the Form separation plane (x, z) of the blow mold cavities (4) over an angle of ± 45 ° maximum extends. A method according to claim 1, characterized in that the transmission elements (19) act on force application points (20) on the periphery of the elastically deformable sleeves (17) which lie in the mold parting plane (x, z) of the Blasformkavitäten (4). Method according to one of claims 1 to 3, characterized in that the transmission elements (19) in an adjusting movement of their associated drive (18) act on an outer circumferential surface of the sleeves (17) and that the sleeves (17) each arranged on at least one circumferentially Counter bearing (23) supported and / or tied. Method according to one of Claims 1 to 4, characterized in that the transmission element (19) assigned to an individual drive (18) has kinematic coupled elements (24, 24 ') which act in pairs on the sleeve (17) and in an adjusting movement of the individual drive (18) exert on both sides radial compressive forces or tensile forces on the associated sleeve (17). Method according to one of claims 1 to 4, characterized in that the transmission elements (19) transmit radial tensile forces on the lateral surface of the sleeves (17). Method according to one of claims 1 to 3, characterized in that the extrusion tools (2) each two program-controlled individual drives (18) are assigned by means of associated transmission elements (19) only on the elastically deformable sleeve (17) of the associated extrusion tool (2) act and tensile forces and / or pressure forces on a shell surface the sleeve (17) exercise, and that by program controlled adjusting movements of the two individual drives (18) the sleeve (17) is deformed, pivoted or radially displaced. A method according to claim 7, characterized in that the sleeve (17) is deformed by opposing, in the amount equal adjustment paths of acting on them transfer elements (19) or deformed by the amount different adjustment paths and pivoted in the direction of the deformation axis or radially displaced or that the sleeve is pivoted or displaced radially by the same direction, equal adjustment movements of the transmission elements (19) without deformation. Method according to one of claims 1 to 8, characterized in that basic settings are made on the extrusion tools (2), wherein in the course of these settings, the sleeves (17) are pre-formed and / or the position of the sleeves (17) is corrected and / or the nozzle body (7) and the mandrel (6) are adjusted relative to each other. Multiple extrusion head, in particular for carrying out the method according to one of Claims 1 to 9, which has at least two extrusion tools (2) arranged next to one another with a nozzle gap (s) bounded by a mandrel (6) and a nozzle body (7),
wherein the extrusion dies (2) are each provided with at least one elastically deformable sleeve (17) which forms a wall section of the die gap (s) and is arranged in the nozzle body (7) of the extrusion die (2),
wherein each extrusion tool (2) is assigned at least one program-controlled individual drive (18), which by means of a transmission element (19) acts only on the elastically deformable sleeve (17) of the associated extrusion tool (2), and
wherein the transmission elements (19) in each case engage in the area between adjacent extrusion tools (2) and are effective there at a peripheral portion of the elastically deformable sleeve (17) associated with the individual drive (18). Multiple extrusion head according to claim 10, characterized in that the transmission elements (19) act on an outer circumferential surface of the sleeves (17). Multiple extrusion head according to claim 10 or 11, characterized in that the transmission elements (19) act on an outer circumferential surface of the sleeves (17) during an adjusting movement of their associated individual drive (18) and in that the sleeves (17) are each attached to at least one abutment ( 23) are supported and / or tethered. Multiple extrusion head according to one of Claims 10 to 12, characterized in that the transmission element (19) associated with a single drive (18) has kinematically coupled elements (24, 24 ') which act in pairs on the sleeve (17) and in an adjusting movement of the individual drive (18) exert pressure or tensile forces on the associated sleeve (17) on both sides. Multiple extrusion head according to claim 13, characterized in that the elements (24, 24 ') of the transmission element (19) in a Adjusting movement of the single drive (18) perform an opposing forceps movement. Multiple extrusion head according to claim 13 or 14, characterized in that the elements (24, 24 ') hinged to the sleeve (17) and connected via a toggle lever arrangement (36) to the single drive (18). Multiple extrusion head according to one of claims 10 to 14, characterized in that the transmission elements (19) are designed as slides (28), the slides (28) each having a control surface which cooperates with a mating surface on the associated sleeve (17). Multiple extrusion head according to one of claims 10 to 14, characterized in that the transmission elements (19) are designed as an eccentric arrangement, each having at least one rotatably mounted eccentric shaft (38). Multiple extrusion head according to claim 16 or 17, characterized in that the transmission elements (19) act on control surfaces (32, 32 ') which are connected to the sleeves (17) and in an adjusting movement of the transmission elements (19) tensile forces on the sleeves (17 ) transfer. Multiple extrusion head according to one of Claims 16 to 18, characterized in that the transmission elements (19) act on control surfaces (32, 32 ') which are connected to the sleeves (17) and in the case of an actuating movement of the transmission elements (19) as a function of the control path a tensile force or a compressive force on the sleeves (17) transmitted. Multiple extrusion head according to one of claims 16 to 19, characterized in that the transmission elements (19) engage in connection elements (31) which are connected to the sleeves (17) and interact with the transmission elements control surfaces (32, 32 ') for transmission have radial compressive or tensile forces. Multiple extrusion head according to one of Claims 10 to 14, characterized in that the transmission elements (19) are designed as rotary rings (34) which have at least one control surface (33) on a peripheral surface adjacent to the sleeves (17), and in that the control surface (33) 33) cooperates with a counter-surface (35) on the sleeve (17) during a rotational movement of the rotary ring (34) and exerts pressure on the associated sleeve (17). Multiple extrusion head according to one of claims 10 to 14, characterized in that the transmission elements (19) have a joint arrangement which acts on the sleeve (17). Multiple extrusion head according to claim 10 or 11, characterized in that each extrusion tool (2) of the multiple extrusion head (1) is associated with two program-controlled individual drives (18) which act by means of associated transmission elements (19) only on the elastically deformable sleeve (17) of the associated extrusion tool and tensile forces or compressive forces on a lateral surface of the sleeve (17) exercise, and that by program-controlled adjusting movements of the two individual drives, the sleeve (17) can be deformed, pivoted or radially displaced. Multiple extrusion head according to one of claims 10 to 23, characterized in that the transmission elements (19) comprise a linkage (44). having a setting stroke (h ₁ ) of the rod (44) connected to the individual drive (18) in a on the elastically deformable sleeve (17) effective smaller travel (h ₂ ). Multiple extrusion head according to claim 24, characterized in that the linkage (44) comprises a lever (45) which is pivotally mounted at one end in a bearing (50) and articulated at its other end with an actuator (46) of the single drive (18 ), and that between the lever (45) and the elastically deformable sleeve (17) there is provided a transmission element (47) for transmission of motion, which at a coupling point (48) between the force application point (49) of the lever (45) acting single drive (18) and the end bearing (50) to the lever (45) is connected. Multiple extrusion head according to one of claims 10 to 25, characterized in that the nozzle body (7) are arranged horizontally adjustable or tiltable and that at least one drive is provided to the nozzle body (7) relative to the mandrels (6) of the extrusion dies (2). to adjust. Multiple extrusion head according to Claim 26, characterized in that the direction of action of the drive acting on at least one nozzle body (7) is aligned with the deformation axis predetermined by the force application points (20) of the transmission elements (19) or extends parallel to a deformation-neutral axis of the sleeves (17) , Multiple extrusion head according to one of claims 10 to 27, characterized in that the extrusion dies (2) are individually associated and having independently operable actuating elements (26, 27) for changing a basic setting of the nozzle gap geometry. Multiple extrusion head according to claim 28, characterized in that on the transmission elements (19) adjusting elements (26, 26 ') are arranged, wherein by actuation of an adjusting elements (29) the basic setting of the extrusion die (2) by a pre-deformation and / or a position correction of the sleeve (17) is changeable.

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